mid-13c., from Old French precios "precious, costly, honorable, of great worth" (11c., Modern French précieux), from Latin pretiosus "costly, valuable," from pretium "value, worth, price" (see price (n.)). Meaning "over-refined" in English first recorded late 14c. In Johnson's day, it also had a secondary inverted sense of "worthless." Related: Preciously; preciousness.